Hyndman, Pa., Aug 2 (Reuters) - Rail cars carrying gas and sulfur on a CSX Corp freight train skidded off the tracks and burst into flames on Wednesday in a small Pennsylvania town, forcing hundreds of residents to flee their homes as firefighters fought the blaze.

No injuries were reported after the crash in Hyndman, about 100 miles southeast of Pittsburgh. CSX warned customers service disruptions would last for a week over a nearly 80-mile stretch between Connellsville, Pennsylvania, and Cumberland, Maryland.

CSX said 32 cars derailed as the train moved through the town just before 5 a.m. There was no word on what caused the crash.

A freight car skidded into a garage that caught fire, and at least two train cars were still ablaze almost 12 hours later, said Bedford County emergency dispatcher Mike Steele.

CSX said one rail car containing liquefied petroleum gas and one car containing molten sulfur leaked and were on fire.

Authorities ordered the evacuation of residents in a one-mile radius, which encompasses most of the town, as emergency crews worried about the risk of an explosion, Steele said.

Among the residents driving out of town was 53-year-old Shannon Shoemaker, who said his whole family lives within 100 yards of the derailment site.

"They all got out safely, thank God for that," Shoemaker said.

This was the third derailment for a CSX train since last November. It came two days after CSX Corp CEO Hunter Harrison apologized to customers for service disruptions and said some railroad employees were resisting planned cost-cutting measures.

The train of five locomotives and 178 rail cars was traveling from Chicago to Selkirk, New York, CSX said. It said 128 cars carried mixed freight, including construction materials, paper and wood pulp.

John Risch, spokesman for the transportation division of the SMART Union, which represents CSX conductors, said it is incredibly difficult for a small crew to handle a train with 178 cars.

"It's hard to keep track of where the train is, especially as it snakes behind you for more than two miles," Risch said by phone. "I am not suggesting the length of the train caused the accident but it could have been a contributing factor."

On Monday, Harrison, the CSX chief executive officer, told customers in a memo that some employees were resisting aggressive cost-cutting measures at the No. 3 U.S. railroad.

Authorities closed roads and issued temporary restrictions on low-flying aircraft, Pennsylvania Governor Tom Wolf's office said, adding that Wolf was on scene in Hyndman. No public water supplies or waterways were affected, his office said.

The governor's office said about 1,000 people had to leave their homes. An emergency shelter was assembled at a local school, staffed by aid workers from the American Red Cross and the Salvation Army, authorities said.

CSX said company hazardous substance experts were working with firefighters at the scene to contain leaks and minimize environmental damage.

Investigators with the National Transportation Safety Board and the Federal Railroad Administration were in Hyndman, the agencies said.

In March, a CSX freight train containing sulfuric acid and other dangerous materials partially derailed near Newburgh, New York, though the dangerous substances did not leak. Last November, two CSX trains collided and derailed in central Florida, injuring two crew members.

The probes into those incidents were still under way, said Federal Railroad Administration spokesman Warren Flatau.

After the New York incident, the Times Herald-Record newspaper cited officials and witnesses as saying the train derailed after striking a forklift being driven across the tracks. (Additional reporting by Eric M. Johnson in Seattle, David Shepardson in Washington and Jarrett Renshaw in New York; writing by Eric M. Johnson; Editing by David Gregorio)